The cpu is fine for gaming. The only cases I can think where it would make a difference are:
1- 120 hz monitor, i5 will have a better timing achieving 120 fps
2- BF3 multy with 64 players
+1 for the 7850 btw. And I think you should look into a cpu cooler if you run into trouble, the 8320 is unlocked, and you can compensate the difference towards an i5 with some good old OC
The 7850 is faster thank gtx 660 in some games, others the exact opposite, but it in an excellent OCer (generally) and is less limited by bandwith than is the gtx 660.